Current Serbian design codes: Transferring from a deterministic to a semi- probabilistic approach

Abstract

The Serbian design code for reinforced concrete structures is somewhat out-of-date in its approach to structural design. In this paper, a study into the possible transition to a semi-probabilistic approach is presented. Firstly, the implicit reliability indices in the current Serbian reinforced concrete design code are determined for three design situations - bending, axial compression and shear and for various cases within each of them. The implicit reliability indices show that the Serbian design code is more conservative than Eurocode 2, but that design for shear without stirrups has a significantly low reliability index (2.27). Secondly, a calibration procedure was implemented in order to obtain partial safety factors for a target reliability index of 4.8 (calculated as the average of the implicit reliability indices). The obtained partial safety factors are ready-for-use with the current Serbian design code and, as expected, are higher than those in Eurocode 2.

Srpski propis za proračun armiranobetonskih konstrukcija je relativno zastareo u svom pristupu. U ovom radu sprovedena je analiza mogućnosti prelaska na polu-probabilistički pristup definišući i parcijalne faktore sigurnosti i na strani nosivosti. Prvo su određeni indeksi sigurnosti, implicitno sadržani u važećem propisu, za tri proračunske situacije - savijanje, centrični pritisak i smicanje i za nekoliko slučajeva u okviru svake situacije. Izračunati indeksi sigurnosti pokazuju da je važeći srpski propis konzervativniji od Evrokoda 2 osim proračunski slučaj smicanja bez armature koji ima izuzetno nizak indeks sigurnosti (2.27). U drugom delu je primenjen postupak kalibracije radi dobijanja parcijalnih koeficijenata sigurnosti za ciljani indeks sigurnosti od 4.8 (dobijen kao srednja vrednost implicitnih indeksa sigurnosti). Rezultujući parcijalni koeficijenti sigurnosti su, očekivano, veći nego oni u Evrokodu 2, a moguća je njihova direktna upotreba uz važeći srpski propis.